Radio receiver that changes function according to the output of an internal voice-only detector

ABSTRACT

A radio receiver includes a voice-only detection mechanism that detects when the current radio station is transmitting mostly voice, and that changes the function of the receiver depending on whether or not the current radio station is transmitting mostly voice. In a first embodiment, the radio receiver mutes its audio output when the voice-only detection mechanism detects a voice broadcast, or mutes its audio output when the voice-only detection mechanism detects a music broadcast. In a second embodiment, the radio receiver changes to a different radio station when a voice-only signal is detected, or when a music signal is detected. The second embodiment preferably includes a spectrum analyzer that can store a frequency spectrum “signature” of a radio signal, and a second tuner that scans the available radio stations for a signal that matches the stored signature.

RELATED APPLICATION

This patent application is a continuation of U.S. Ser. No. 09/735,341entitled “RADIO RECEIVER THAT CHANGES FUNCTION ACCORDING TO THE OUTPUTOF AN INTERNAL VOICE-ONLY DETECTOR” filed on Dec. 12, 2000, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention generally relates to radio broadcasting and morespecifically relates to radio receivers.

2. Background Art

For many decades, radio has been an important part of life in the UnitedStates, providing countless hours of news, entertainment, and music.Radio receivers typically receive radio signals from local radiostations that transmit their signal over an assigned frequency at orbelow a prescribed power level. Due to the power limitations imposed onradio transmissions, the range of a radio station is very limited. Whena person gets into a vehicle to drive a long distance and tunes to aradio station, the reception on that radio station will typicallydegrade within an hour or two, forcing the driver to seek a new radiostation. Manually scanning all the radio stations on the dial can bevery annoying to a driver that wants to hear a particular type of radioprogram while driving. If the listener prefers country music, thelistener must stop and listen to each station to determine if thestation is playing country music. Likewise, if the listener prefers talkradio, the listener must listen to each station to determine whether thestation is playing music or not, and if not, to determine whether thestation is a talk radio station or is simply broadcasting a voicecommercial or the voice of the disc jockey talking between songs.

Another aspect of known radio receivers is that there is currently noway to distinguish between different types of signals on the same radiostation. In other words, once tuned to a radio station, the radioreceiver simply transmits the audio output for that radio station to thelistener. There is currently no known way to change the operational modeof a radio receiver based on the frequency spectrum of the signal beingtransmitted.

Without a way for a user to mute unwanted radio programs or changestations to a different station that is playing the desired type ofradio program, users will be forced to either listen to undesiredprograms, or to manually scan stations until a desired program is heard.

DISCLOSURE OF INVENTION

According to the preferred embodiments, a radio receiver includes avoice-only detection mechanism that detects when the current radiostation is transmitting mostly voice, and that changes the function ofthe receiver depending on whether or not the current radio station istransmitting mostly voice. In a first embodiment, the radio receivermutes its audio output when the voice-only detection mechanism detects avoice broadcast. The audio output can be enabled once again when thevoice-only detection mechanism detects a non-voice signal. The firstembodiment thus allows commercials and disk jockey talk to beautomatically muted, with the volume returned to its previous level whenmusic resumes. In a variation of the first embodiment, the radioreceiver mutes its audio output when the voice-only detection mechanismdetects a non-voice broadcast, and enables the audio output when thevoice-only detection mechanism detects a voice signal, thereby allowinga listener to listen to talk radio while muting musical commercials. Ina second embodiment, the radio receiver changes to a different radiostation when a voice-only signal is detected. The second embodimentpreferably includes a spectrum analyzer that can store a frequencyspectrum “signature” of a radio signal, and a second tuner that scansthe available radio stations for a signal that matches the storedfrequency spectrum signature. This allows the radio receiver toautomatically switch from a first radio station to a second radiostation that is playing music that matches the preferences of thelistener when the voice-only detection mechanism detects a mostly voicesignal. In a variation of the second embodiment, the radio receiver mayautomatically switch from a first talk radio station to a second talkradio station when the voice-only detection mechanism detects a musicalsignal, indicating a commercial.

The foregoing and other features and advantages of the invention will beapparent from the following more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF DRAWINGS

The preferred embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, where likedesignations denote like elements, and:

FIG. 1 is a front view of a prior art radio receiver;

FIG. 2 is a front view of a radio receiver according to the preferredembodiments;

FIG. 3 is a block diagram of the prior art radio receiver in FIG. 1;

FIG. 4 is a block diagram of the radio receiver of FIG. 2 in accordancewith one preferred embodiment;

FIG. 5 is a schematic diagram showing one specific implementation of theDJVO detector of FIG. 4 in accordance with the preferred embodiments;

FIG. 6 is a block diagram of the radio receiver of FIG. 2 in accordancewith another preferred embodiment;

FIG. 7 is a block diagram showing functions that may be performed inaccordance with the preferred embodiments;

FIG. 8 is a flow diagram that shows the steps that may be performed inaccordance with the preferred embodiments to change the operational modeof the radio receiver when mostly voice is detected;

FIG. 9 is a flow diagram of one specific implementation of step 810 inFIG. 8;

FIG. 10 is a flow diagram of another specific implementation of step 810in FIG. 8; and

FIG. 11 is a flow diagram of a method for changing operational modes ofa radio receiver in accordance with the preferred embodiments;

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, a radio receiver 100 in accordance with the priorart includes keys (or buttons) that change the function of the receiver100, as well as a display 120. The buttons include a power button 130, avolume up button 132, a volume down button 134, an AM radio selectbutton 136, an FM radio select button 138, and a select button 142 forselecting different modes, such as balance and fade adjustment, etc.Also included is a station up key 144, a station down key 146, andnumerous station preset keys 148. Note that the buttons may take ondifferent functions according to the selected mode for the radioreceiver 100. For example, if balance mode is selected using selectbutton 142, the volume up and down buttons 132 and 134 may be used toadjust the balance between the left and right speakers.

Display 120 generally includes information about the station currentlybeing listened to, and may include a clock display as well, as shown inFIG. 1. For the example of FIG. 1, the selected radio station is 95.1FM. Radio receiver 100 thus provides to the user a visual indication ofwhat station is currently tuned in.

The preferred embodiments improve upon the prior art by providing avoice-only detector that detects when the broadcast signal from thecurrent station becomes mostly voice, and provides a first outputindication when the current station becomes mostly voice and a secondoutput indication when the current station is no longer mostly voice. Inaddition, a radio receiver in accordance with the preferred embodimentsmay include a mechanism for setting a preferred frequency spectrumsignature, and for automatically tuning to a different station whosecurrent signal matches the preferred frequency spectrum signature whenthe current station no longer matches the preferred frequency spectrumsignature. In this manner the radio receiver of the preferredembodiments may automatically switch to a different radio station thatmatches the preferred frequency spectrum signature, and may provide a“smart scan” feature where only the radio stations that have signalsthat match the preferred frequency spectrum signature are tuned in.

Referring now to FIG. 2, a radio receiver 200 in accordance with thepreferred embodiments includes many similar buttons as on the prior artreceiver 100 of FIG. 1 for the sake of convenience and consistency indiscussing the differences between the prior art and the preferredembodiments. The primary difference between prior art receiver 100 andreceiver 200 is control inputs 250-280 that allow the radio receiver 200to alter its operational mode when the frequency spectrumcharacteristics of the radio transmission changes. Note that thisreceiver 200 could be a stationary receiver (e.g., for a home stereosystem) or a mobile receiver (e.g., for a car stereo system). For thespecific example in FIG. 2, display 220 displays the same informationfor the current station as was displayed in the prior art display 120 inFIG. 1.

Radio receiver 200 includes a “Preference On” button 250 that, whenpushed, enables the radio receiver to prefer a signal that matches aselected frequency spectrum signature, and that causes the radioreceiver 200 to change its operational mode when the signal currentlytuned to does not match the selected frequency spectrum signature. Inone aspect of the preferred embodiments, a “smart scan” is now possible,where the radio receiver automatically detects which radio station (ifany) is playing a program that matches the listener's preference. Thus,if the user prefers soft rock and selects soft rock as the preferredtype of music, and if the preference on button 250 is pushed and theskip to preference button 280 is pushed, the radio receiver 200 willautomatically scan to the next station that is broadcasting a soft rocksong rather than stopping at each station. The manual scan overridebutton 252 allows a user to override the preference settings to allowthe user to listen to a program that does not match the preferencesettings. Thus, a user with a soft rock preference set may still listento news or weather reports by pushing the manual scan override button252.

Knobs 260 and 262 allow the listener to customize the threshold valueand time, respectively, of a DJVO detector, which stands for Disc JockeyVoice Only. The DJVO detector is one specific implementation of avoice-only detection mechanism that allows discriminating between thefrequency content of different radio signals, and changing theoperational mode of radio receiver 200 according to the detectedfrequency content. The threshold for what constitutes “mostly voice” maybe adjusted using knob 260. The time period for which a signal must bemostly voice before changing the DJVO outputs is adjustable using knob262. An indicator 264 indicates when the DJVO detects a mostly voiceprogram. If the radio receiver is set to mute the audio output when amostly voice signal is received, indicator 264 serves as a muteindicator that helps the listener to visually distinguish between amuted program and a program that has long pauses of silence.

A set current to preference button 270 may be used to store thefrequency spectrum characteristics of the current radio station beinglistened to as the preferred type of music. This is a very quick andeasy way for a user to select a particular type of radio program as thepreferred type. In the alternative, a user may select from severalpreset types of programs that are pre-programmed into the radio receiver200 by selecting the desired type of program from a menu shown ondisplay 220.

The skip to preference button 280 is used to implement a “smart scan” ofradio stations that are currently broadcasting a signal that hasfrequency spectrum characteristics that match the preferred type ofprogram that the user has selected. This smart scan ability greatlyimproves the convenience of using the radio receiver 200 byautomatically ignoring all of the radio stations that are not currentlybroadcasting a signal that matches the preferred type of program thathas been selected by the listener.

The term “radio program” is used very broadly herein to refer to anyprogram or portion of a program that may be transmitted via radiosignals. A radio program may include a song, a talk show program, asporting event, a news report, etc.

Referring now to FIG. 3, radio receiver 100 includes a radio processor310 coupled to keys/buttons 320, a power source 330, an antenna 340, atuner 350, a memory 360, a display 370, and an audio output 380. Thekeys/buttons 320 are the various keys and buttons that control thefunction of radio receiver 100, including the buttons shown in FIG. 1.The power source 330 is any suitable power source. For stationary radioreceivers, the preferred power source is line power received fromplugging a power cord into a standard power receptacle. For portableradio receivers, such as those located in vehicles, the preferred powersource is 12 volt DC power from the vehicle's electrical system.

Antenna 340 is an antenna that is designed to receive AM and FM radiobroadcasts. Tuner 350 is used to distinguish between the different radiobroadcasts on the AM and FM frequency bands. Tuner 350 is used to selecta current radio station to listen to, and this signal is then processedby radio processor 310 and output to the audio output 380.

Memory 360 includes station presets 362. Station presets 362 are thestations that are assigned to the preset buttons 148 of FIG. 1. Thestation presets are typically programmed by a user to allow instantlytuning to the station at the press of a preset button, as is known inthe art.

Radio processor 310 is coupled to an audio output 380, which is suitablycoupled to an appropriate audio device, such as one or more speakers.The audio output 380 is the radio program that is converted to audiosignals so the radio program can be heard by the user. Audio output 380is typically a low-level signal that is subsequently amplified and thensupplied to speakers for the listener to hear the radio programcurrently playing on the selected radio station. Note, however, that theaudio output 380 may be a signal that is amplified, either by radioprocessor 310 or by suitable circuitry coupled to radio processor 310 ortuner 350, and that the muting of the audio signal may comprise mutingof a low-level audio signal before amplification, or muting of theamplified audio signal. Of course, muting of a low-level audio signalalso accomplishes the muting of the amplified audio signal as well.

Display 370 includes the station display 372 that displays thecurrently-tuned station, such as 95.1 FM as shown in FIG. 1.

Referring now to FIG. 4, a radio receiver 200 in accordance with thepreferred embodiments includes a radio processor 410, keys/buttons 420,a power source 430, a spectrum analyzer 432, an antenna 440, a maintuner 450, a scanning tuner 452, a memory 460, a display 470, an audiooutput 480, a full wave rectifier 490, and a voice-only detector 492,referred to herein as a DJVO detector. DJVO detector 492 allowsdiscriminating between the frequency content of different radio signals,and changing the operational mode of radio receiver 200 according to thedetected frequency content.

The keys/buttons 420 include the keys and buttons shown in FIG. 2 anddiscussed above. The power source 430 is preferably similar to the powersource 330 in FIG. 3. The spectrum analyzer 432 is preferably anoff-the-shelf frequency spectrum analyzer, such as those used in graphicequalizers. One suitable spectrum analyzer is the Hitachi 5G1HD38755A67. Spectrum analyzer 432 takes an audio input, such as frommain tuner 450 or scanning tuner 452, and outputs values for a number ofdifferent frequency bands (typically seven or nine) that characterizethe frequency spectrum of the input signal. Radio processor 410 readsthe output of spectrum analyzer 432, thereby allowing the radioprocessor 410 to determine the frequency spectrum of an input signal ofinterest (e.g., from either main tuner 450 or scanning tuner 452). Thisfrequency spectrum may then be compared against a selected frequencyspectrum signature to see if they match within predetermined criteria.

Antenna 440 is coupled to both main tuner 450 and scanning tuner 452.The most preferred embodiment includes two different tuners so that thescanning tuner 452 can be constantly scanning other stations for signalsthat match the selected frequency spectrum signature while the maintuner 450 is tuned to a station that the user is currently listening to.By providing two separate tuners, the scan for a new station that has asignal that matches the selected frequency spectrum signature may bedone very quickly. Of course, a single tuner could be used to scan for asuitable station after the radio processor 410 decides a new station isneeded, but the response time for finding a new suitable station wouldcause a noticeable delay in switching between the current station andthe next desirable station.

Memory 460 is suitably similar to memory 360 shown in FIG. 3 describedabove. Display 470 includes a station display 472 and a parameterdisplay 474. Parameter display 474 allows a user to view menu choicesfor selecting a pre-defined type of radio program as the selectedfrequency spectrum signature. In addition, parameter display 474 mayinclude indicators that indicate the state of the various controlbuttons and keys 250-280.

Audio output 480 is suitably similar to audio output 380 for the priorart radio receiver discussed above with reference to FIG. 3. The audiooutput from radio processor 410 is fed into a full wave rectifier 490,which converts the audio signals to a rectified waveform. Most modernradio stations use a compander (compressor/expander) that increases(expands) signal strength when the sound becomes quiet and that cuts(compresses) the signal strength when the sound becomes loud. A voiceprogram run through a compander will thus have deeper periods of silencebetween words and sentences due to delay in compander transitions thatwill not exist in a musical program, and that can therefore be used toidentify when a signal is mostly voice. Note that the application of thepresent invention is not limited to radio signals that use a compander.Proper adjustment of the apparatus and method of the present inventionwill result in proper operation even in the absence of a compander.

The output of the full wave rectifier 490 goes to a DJVO detector 492.DJVO detector 492 is one specific implementation of a voice-onlydetector mechanism. When DJVO detector 492 detects that the full-waverectified audio output falls below a preset threshold value (DJVOthreshold value) for a predetermined period of time (DJVO timethreshold), it asserts its DJVO trigger signal to the radio processor410, which signals the processor 410 to change the operational mode ofthe radio receiver 440. Depending on the user's selected preferences,the radio processor 410 may simply mute the audio output 480, or mayswitch main tuner 450 to a new radio station identifier by scanningtuner 452 to be playing a program that matches the user's selectedprogram type.

One suitable implementation of the DJVO detector in accordance with thepreferred embodiments is shown in FIG. 5. The audio output that has beenfull wave rectified is input into a voice comparator 510. Connected tothe same input is a resister RI and a capacitor CI whose valuesdetermine a time constant that is preferably 10-25 milliseconds (ms).This signal is compared to a voice threshold signal that is preferablyset to a value that the compander low noise level will cross thethreshold but normal musical programs will not. The voice comparator 510asserts its output high to signal a dropout below the voice thresholdvalue. When the voice comparator output is high, the DJVO display LED520 is lit to indicate that the DJVO detector is currently detecting adrop-out.

The dropout signal in FIG. 5 is then fed to control logic 530 that iscoupled to a counter 540 and a timer 550. The counter 540 preferably hasa maximum count that may be selected and adjusted by the user, but afixed counter could be used as well. The timer 550 has a period that isadjustable by the user using DJVO timer adjust. Control logic 530 is asimple state machine that could be implemented in any suitable manner,including discrete logic or programmable logic devices. When a dropoutfirst occurs (i.e., on the first rising edge of the dropout signal), thecontrol logic starts the timer by asserting the enable signal to thetimer, and starts the counter counting the dropouts by negating itsreset output to the counter (step 1). If the voice comparator detectsthat the counter is at its maximum value before the timer times out, thecontrol logic asserts its DJVO trigger output (step 2) to the radioprocessor to indicate that a change in operational mode is needed. Oncethe DJVO trigger output is asserted, it remains asserted until thecounter has a count of zero when the timer times out (step 3). Becausestep 2 of the control logic requires a maximum count to assert the DJVOtrigger output, and because step 3 of the control logic requires a countof zero before de-asserting the DJVO trigger output, the DJVO detectorof FIG. 5 provides hysteresis that assures the DJVO trigger output doesnot change excessively around the threshold.

FIG. 6 illustrates an alternative embodiment that is similar in functionto the radio receiver 400 of FIG. 4, but implements these functions in adifferent way. Radio receiver 600 performs much of the analysis of therectified audio output in software. As a result, radio processor 610takes the full wave rectified audio output signal and processes it tosee if the operational mode of the radio receiver needs to change. Thememory 660 thus includes the station presets 662 as before, butadditionally includes a DJVO detector 664 implemented in software thatoperates according to a voice threshold 665, voice comparator 666, timerthreshold 667, and timer 668 to determine when to change operationalmodes. Implementing the DJVO in software reduces the hardware, but atthe cost of software that is significantly more expensive to develop.Note that memory 660 also includes a spectrum analysis mechanism 669that analyzes the audio outputs of main tuner 650 and scanning tuner 652to produce a frequency spectrum characterization for these signals,rather than providing a hardware spectrum analyzer.

FIG. 7 shows a block diagram showing a radio receiver 700 with functionsthat are needed to accomplish both the muting and smart scanningdescribed in the preferred embodiments. The tuner 710 receives the radiosignals, spectrum analyzer 720 analyzes the radio signals and generatesa frequency spectrum characterization or “signature” for the radiosignals. Rectifier 730 corresponds to the full wave rectifier 490 and690 of FIGS. 4 and 6, respectively. Voice only detection mechanism 740corresponds to the DJVO detector 492 in FIG. 4 or 664 in FIG. 6. Byproviding these functions as described herein with respect to thehardware implementation in FIG. 4, the radio receiver 700 may change itsoperational mode (such as muting the signal or changing to a newstation) when the incoming radio signal no longer matches the preferredfrequency spectrum signature. Note that the general block diagram ofFIG. 7 describes both the mostly hardware implementation of FIG. 4 aswell as the mostly software implementation of FIG. 6.

Referring now to FIG. 8, a method 800 in accordance with the preferredembodiments begins by selecting a preferred frequency spectrumsignature, referred to in shortened form as a program signature (step810). The current radio audio signal is then analyzed (step 820). If thecurrent radio audio signal is mostly voice (step 830=YES), theoperational mode of the radio receiver is changed by either muting theaudio signal or by changing stations to the next station that matchesthe preferred program signature (step 840). If the current radio stationis not mostly voice (step 830=NO), the monitoring of the current radioaudio signal continues (step 820). Note that a variation of method 800switches the YES and NO labels of step 830, allowing a listener tolisten to talk radio while muting musical commercials, or changingstations when a musical commercial is detected.

Referring to FIG. 9, one suitable way to implement step 810 in FIG. 8 isto select a preferred musical signature from a list of predefinedmusical signatures that is preferably displayed to a user on display 220of FIG. 2. Referring to FIG. 10, another suitable way to implement step810 in FIG. 8 begins by selecting a radio station (step 1010),performing a spectrum analysis and determining a normalized frequencyband output for the selected radio station (step 1020), and by savingthe frequency band output as the preferred musical signature (step1030). Steps 1010-1030 of FIG. 10 are the steps that are performed whena user selects a radio station and presses the “set current topreference” button 270 shown in FIG. 2.

Referring now to FIG. 11, one specific implementation of step 820 inFIG. 8 is shown. We assume that the tuner is tuned to a current radiostation (step 1105). A new radio station is then selected and tuned in(step 1110), preferably using the scanning tuner. A spectrum analysis isthen performed, and the results are normalized to a frequency band forthe new radio station (step 1120). The band output values thatcorrespond to the preferred frequency spectrum signature are thensubtracted from the new radio station normalized frequency band output(step 1130). If the frequency band difference is within a definedtolerance (step 1140=YES), step 1160 then determines if there are morefrequency bands to process. If the frequency band difference is notwithin the defined tolerance (step 1140=NO), a count of bands outside ofthe defined tolerance is incremented (step 1150). When there are no morefrequency bands to process (step 1160=NO), step 1170 determines whetherthe radio station is within a defined tolerance from the preferredprogram signature (step 1170). If not (step 1170=NO), the next radiostation is selected (step 1110), and the process continues, searchingfor a station with a frequency spectrum that matches the selectedprogram signature. If so (step 1180=YES), the current radio station isan acceptable station with respect to the defined tolerances, so anacceptable station has been found (step 1180).

The preferred embodiments disclosed herein greatly improve theconvenience of using a radio receiver by analyzing an audio output of aradio station, and by either muting the audio output or changing to adifferent station when the audio output indicates the broadcast is notlonger the preferred type.

One skilled in the art will appreciate that many variations are possiblewithin the scope of the present invention. Thus, while the invention hasbeen particularly shown and described with reference to preferredembodiments thereof, it will be understood by those skilled in the artthat these and other changes in form and details may be made thereinwithout departing from the spirit and scope of the invention.

1. A radio receiver comprising: a tuner that provides an audio outputfor a selected radio station; a voice-only detection mechanism thatmonitors the audio output of the tuner, and that provides a first outputindication when the audio output of the tuner is mostly voice, and thatprovides a second output indication when the audio output of the tuneris mostly music; and a radio processor coupled to the voice-onlydetection mechanism, the radio processor changing an operational mode ofthe radio receiver according to the first and second output indicationsof the voice-only detection mechanism.
 2. The radio receiver of claim 1further comprising an amplifier coupled to the audio output of the tunerthat provides an amplified audio signal to at least one speaker, whereinthe radio processor changes the operational mode of the radio receiverby muting the amplified audio signal according to the first and secondoutput indications of the voice-only detection mechanism.
 3. The radioreceiver of claim 2 wherein the radio processor mutes the amplifiedaudio signal when the first output indication is received, and unmutesthe amplified audio signal when the second output indication isreceived.
 4. The radio receiver of claim 2 wherein the radio processormutes the amplified audio signal when the second output indication isreceived, and unmutes the amplified audio signal when the first outputindication is received.
 5. The radio receiver of claim 1 wherein theradio processor changes the tuner to a different radio station accordingto the first and second output indications of the voice-only detectionmechanism.
 6. The radio receiver of claim 1 further comprising at leastone adjustment mechanism that adjusts at least one threshold thatdetermines when the voice-only detection mechanism asserts the first andsecond output indications.
 7. A radio receiver comprising: a tuner thatprovides an audio output for a selected radio station; an amplifiercoupled to the audio output of the tuner that provides an amplifiedaudio signal to at least one speaker, a voice-only detection mechanismthat monitors the audio output of the tuner, and that provides a firstoutput indication when the audio output of the tuner is mostly voice,and that provides a second output indication when the audio output ofthe tuner is mostly music; and a radio processor coupled to thevoice-only detection mechanism, the radio processor muting the amplifiedaudio signal when the first output indication is received, and unmutingthe amplified audio signal when the second output indication isreceived.
 8. A method for changing an operational mode of a radioreceiver, the method comprising the steps of: (A) analyzing an audiooutput of a tuner; (B) providing a first output indication when theaudio output is mostly voice; (C) providing a second output indicationwhen the audio output is mostly music; and (D) changing the operationalmode of the radio receiver according to the first and second outputindications.
 9. The method of claim 8 wherein step (D) mutes anamplified audio signal from the tuner when the first output indicationis received, and unmutes the amplified audio signal from the tuner whenthe second output indication is received.
 10. The method of claim 8wherein step (D) changes the operational mode of the radio receiver bymuting an amplified audio signal from the tuner.
 11. The method of claim8 wherein step (D) changes the operational mode of the radio receiver byunmuting an amplified audio signal from the tuner.
 12. The method ofclaim 8 wherein step (D) changes the operational mode of the radioreceiver by changing the tuner to a different radio station.
 13. Amethod for changing the operational mode of a radio receiver, the methodcomprising the steps of: providing an audio output for a selected radiostation; amplifying the audio output; supplying the amplified audiooutput to at least one speaker, monitoring the audio output; providing afirst output indication when the audio output is mostly voice; providinga second output indication when the audio output is mostly music; andmuting the amplified audio signal when the first output indication isreceived, and unmuting the amplified audio signal when the second outputindication is received.